Author Topic: FLATS QUESTION  (Read 577 times)

Offline dpaul

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FLATS QUESTION
« on: 2018 February 14 01:51:28 »
Hi,

Presently I only take darks and bias frames and no flats. This is because I have to return my 30'' scope to a cabin after observing and the width of the entry means I can't leave a camera/filter wheel sticking out sideways, it will get knocked.

I'm aware of the importance of taking flats with the focus position remaining as per the light frame captures, also the camera rotation itself.
So here's my question:

How accurate must this position be? For example if I carefully remove the camera then return it to the scope the following day without adjusting the focuser 'and' noting the rotational position, will that be good enough. The rotation is probably the hardest to replicate but within 1 or 2 degress ok but no if it has to o.1 degrees?

Thanks

David

Offline RickS

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Re: FLATS QUESTION
« Reply #1 on: 2018 February 14 02:35:37 »
I think that at f/3.5 you'll have a reasonable amount of latitude with the flats and near enough will be good enough.  Give it a try!

Offline msmythers

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Re: FLATS QUESTION
« Reply #2 on: 2018 February 14 07:48:33 »
David

I use a low adhesive tape that is polyester/silicone based to mark interconnecting pieces. It leaves no residue. At work we always scribe marked interconnecting pieces to insure having pieces in as close to the original position without doing things like removable pins or vernier adjusters and so on.


Mike

Offline dpaul

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Re: FLATS QUESTION
« Reply #3 on: 2018 February 14 13:19:50 »
Thanks Mike / Rick

Regards

David

Offline John_Gill

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Re: FLATS QUESTION
« Reply #4 on: 2018 February 14 22:33:49 »
Hi,

Flats are short exposures, so taking 60-100 should be less than 5 minutes.

Look up
John
APM 107/700 apo on CGX mount
ZWO Optics - Autoguiding
ZWO1600mm and filters
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